Assassin bug (family Reduviidae), any of about 7,000 species of insects in the true bug order, Heteroptera (Hemiptera), that are characterized by a thin necklike structure connecting the narrow head to the body.

Assassin bug.

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Assassin bug (Narvesus carolinensis).

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Characteristics of assassin bugs

They range in size from 5 to 40 mm (0.2 to 1.6 inches). An assassin bug uses its short three-segmented beak to pierce its prey and then suck the body fluids from its victims. A characteristic of the family is that the beak is curved and lies in a groove between the front legs. Although assassin bugs are generally black or dark brown, some species are brightly coloured. Most members of the family live outdoors and prey on other insects. However, some suck blood from vertebrates, including humans, and transmit diseases.

Predatory behaviour

Assassin bugs display a range of predatory behaviours and prey on a variety of other insects. The black corsair (Melanolestes picipes), a black-coloured insect about 13 to 20 mm (0.5 to 0.8 inch) long and usually found under stones and bark, can inflict painful bites on humans. The masked hunter (or masked bedbug hunter; Reduvius personatus), when threatened, will also bite humans, causing pain and localized swelling. The masked hunter is widely known for its ability to camouflage itself as a ball of dust during the immature stages, when the body, legs, and antennae become covered with sticky hairs that catch pieces of lint and dust. The brownish black adult, roughly 15 to 22 mm (0.6 to 0.87 inch) long, is commonly found preying on insects, such as bedbugs and flies, in houses. Though originally a central European species, the masked hunter has spread throughout parts of the United States and Canada since its accidental introduction.

Some of the best-known assassin bugs are the members of subfamily Triatominae, commonly known as triatomine bugs or kissing bugs. Some species of triatomine bugs—particularly members of the genera Panstrongylus, Rhodnius, and Triatoma—are carriers of the protozoan parasite Trypanosoma cruzi, which causes Chagas disease. Triatomines can survive in a variety of habitats, including underneath rocks and bark, inside the nests of other animals, and inside houses. The Old World species Triatoma rubrofasciata, for example, has been found living in houses as well as in chicken coops and other structures in North America. Rhodnius prolixus is a major vector of Chagas disease in South and Central America. It also has been much used in insect physiology and disease research.

The genusApiomerus, which contains species known commonly as bee assassins or bee killers, is among the largest genera in family Reduviidae. Species of Apiomerus frequent flowering plants, where they coat their legs with sticky plant resins and wait for their prey. The sticky resins allow the assassins to readily capture other insects, particularly bees. Plant resins also appear to play a role in maternal care among certain Apiomerus species.

The wheel bug (Arilus cristatus) is recognized by the notched semicircular crest on the top of the thorax. The adult is brown to gray and large, about 25 to 36 mm (1 to 1.5 inches); the nymph is red with black marks. Wheel bugs occur in North America, are predaceous on other insects, and have a painful bite if handled. The venomous saliva is pumped into a victim through a channel in the wheel bug’s beak. The digested body fluids of the prey are then pumped into the wheel bug’s stomach through another channel in the beak.

The thread-legged bug Emesaya brevipennis, of which there are three subspecies, is about 33 to 37 mm (1.3 to 1.5 inches) long and is usually found on trees or in old buildings. It has long threadlike middle and hind legs, while the shorter, thicker front legs are modified into viselike grasping organs. E. brevipennis occurs in North America.

The thread-legged bug Stenolemus bituberus, which is native to Australia, preys on web-building spiders. It uses one of two different predatory strategies: stalking, in which it approaches its prey slowly and strikes when within range, or luring, in which it plucks the silk threads of the spider’s web with its forelegs, which mimics the behaviour of an insect trapped in the web and thereby attracts the resident spider to within striking distance. The luring predatory behaviour displayed by S. bituberus represents a form of aggressive mimicry.

Several members of the subfamily Holoptilinae, commonly called feather-legged bugs, possess a specialized outgrowth on the abdomen known as a trichome. A secretion released from the trichome attracts ants, which lick the substance and become paralyzed. The feather-legged bug then pierces the ant with its beak and sucks out the body fluids. The behaviour was first reported in 1911 in the Southeast Asian species Ptilocerus ochraceus. It has since been observed among other Holoptilinae species, including Ptilocnemus femoralis and Ptilocnemus lemur.

The species Platymeris rhadamanthus “spits” saliva in reaction to certain disturbances. Saliva is ejected toward an attacker and can travel as far as 30 cm (12 inches). It contains lytic substances, capable of externally digesting the bug’s victims.

The predatory ambush bugs, subfamily Phymatinae, are known for hiding on vegetation and suddenly attacking their prey, capturing their victims with their greatly enlarged fore femurs.

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